When it comes to heroic dogs, Balto is at the top. The famous Siberian His husky inspired the 1995 animated film of New York City as part of a dog sled team that delivered life-saving antivenom to a remote diphtheria-stricken Alaskan town in 1925. It was immortalized as a statue in his central park. And now, Barto’s DNA provides new insight into how genetic diversity affects dog health, past and present.
In a study released Thursday chemistry, Biologists have found that the Baltic’s genome is more diverse and ultimately healthier than most dog breeds today. His genes also suggest that he and his brave canine companions of the 1920s possessed multiple traits that made them better suited to travel and survive in harsh environments. The results reveal that not only canine genetics and ancestry, but also genetic health change over time.
“What we discovered is that the Balts are more genetically diverse and genetically healthier than today’s dog breeds, but they are similar to the working Alaskan dogs we have today. This is to be expected of a group that is bred for work rather than looks, says Catherine Moon, a postdoctoral fellow at the University of California, Santa Cruz, and co-first author of the study. says.
Balto was part of an imported population of Siberian Huskies bred for speed, fitness, and relatively small size. In January 1925, there was an epidemic of diphtheria, a serious bacterial infection that can be fatal if left untreated, in Nome, Alaska. A dog sledding team, including Balto’s, transported vials of diphtheria antivenom on the 674-mile relay from Nenana, Alaska, enduring heavy winds and wind-chill temperatures of -85 degrees Fahrenheit. Using Balto as her husky representative of the 1920s Siberian, Moon and her colleagues wanted to know if the population had specific mutations in the genes that make them such capable sled dogs. was
Researchers sequenced a DNA sample from a Baltic taxidermy specimen at the Cleveland Museum of Natural History. They compared the sequences to those of currently living dog breeds. This includes his three 21st-century sled dogs that ran in his Iditarod, a modern-day annual dog sled race that traces some of the trails of the 1925 antitoxin run. Baltic ancestry is not much different from today’s Alaskan sled dogs, with dogs of Arctic origin sharing his 68% of Baltic ancestry. He also shares a small amount of common ancestry with his Asian dog pedigree. It was shown to have an insulating undercoat and long protective overcoat) and a white tuft on the chest.
The researchers also changed the protein and identified evolutionarily constrained variants. This is a sequence alteration such as a mutation at a specific site in the genome that is highly conserved in many species because the mutation serves an evolutionarily advantageous function. These unique variants are associated with bone and tissue development, including skin thickness, body weight, coordination, and arthrogenesis. Variants of Balto suggest that he had a phenotype, or set of physical traits, optimal for survival in the Arctic. “We were thrilled to see it,” says Moon. “It was impressive in a positive way. It was great to see that the phenotype we predicted from his genotype was somewhat consistent with what we already knew about Barto.”
The team also found that Baltic has adaptations that help digest starch. This is a relatively common trait in modern dog breeds, though not found in wolves. A sled dog’s traditional diet consists primarily of meat, but Moon said Balto also ate starch-rich foods.
“Today’s sled dogs are burning 10,000 calories a day during Iditarod,” says Christina Hansen, assistant professor at the University of Alaska Fairbanks and lead veterinarian for Yukon Quest dog sled racing. For a sled dog weighing between 70 and 70 pounds, a high calorie intake from meat alone means “too much fat and you’re going to have diarrhea,” said Hansen, who was not involved in the new study. I will explain. “Starch is a very good fuel source. We may need to find a way to get more starch into our sled dogs.”
Overall, the Baltic genome is more diverse than most current dog breed genomes, including both dogs bred for appearance and “working” dogs bred for functional traits. was He also had less inbreeding than modern breeds tend to. The number of genetic variations was low. The research team found that some selective breeding was a likely factor in reducing genetic diversity and introducing harmful mutations among current dog breeds. The higher the genetic diversity, the better the ability to adapt to environmental changes and stressors, says Moon.
“We’ve all heard stories of certain breeds that have higher rates of genetic diseases, heart defects, and hip joint abnormalities. That’s what happens when you’re selecting through inbreeding,” he said. says Beth Shapiro, professor of ecology and evolutionary biology. UC Santa Cruz and co-senior author of the new study. “By inbreeding, we’re losing diversity, increasing the chance that bad mutations will become really common in the breed.
Working sled dogs are usually produced by pairing genetically dissimilar parent dogs for speed and endurance. This creates hybrids with more diverse gene populations, which appear to contribute to better health. Hansen says Balto’s genomic findings match what she knows about sled dogs. “They are mostly mixed-breed dogs,” she says. “In general, they are very healthy.”
Today’s sled dogs are “faster and tougher” than those of Baltic times, says Moon. “If you choose functional traits rather than aesthetic traits, you’ll find that you’re genetically diverse and healthy, even though you’re breeding for traits.”
Balto’s genome analysis is part of a broader research project called Zoonomia, a large-scale effort to understand mammalian genetic diversity and evolution. The famous dog genome is an example of what researchers can learn from limited species population data, says Moon. She hopes that her team’s approach and findings can be applied to species that may need greater attention for conservation.
“It’s hard to get resources from an endangered species, where you don’t have a large group that you can sample to see how the population is behaving. It may be limited,” says Moon. “I think this kind of research is very interesting because it means that even a single genome of a species can do a lot of very good research.”
